Sean sets up the drill and Foreman talks him through the brain-drilling process. Wow, I would not want to do that. I can't even reliably hammer nails into walls. I'd probably kill Cate three times over. Sean has some trouble with the drill, and Foreman tells him bone is harder than wood and to force the drill harder. But not too hard! Or else she'll get an unwanted lobotomy. Sean is able to get through the skull, and House tells him to let the fluid drain. CGI blood oozes from the hole and Cate wakes up. She does not scream in pain, though, so I guess having a hole drilled through your skull feels good. Who knew? House allows himself to breath an unguarded sigh of relief.
House goes out to the hall to update the Cottages on Cate's new symptom. Kumar just wants to know why they're outside the office. House points out that the office is their patient room. Kumar may have a new backbone, but he's still dumb. Taub and Mildred throw out a couple guesses that House and Foreman shoot down. Kumar says they're assuming Cate's problems are being caused by clots. Maybe it's something else. He suggests atherosclerosis, where fatty plaques build up on artery walls. If they broke off and entered the blood stream, if could give Cate the same symptoms as clots. House rolls his eyes, saying Cate has zero risks factors for that. "Forget fat, think clots," he says. "NO!" Kumar says, then looks shocked at the words that just came out of his mouth. But he recovers and says it could be a different kind of fat, like fat emboli. House rejects this, saying that would be caused by an unrepaired broken bone and he knows Cate doesn't have any of those. After all, he's seen all of Cate's bones on her X-rays. Or maybe not all of them. "That's what I'm talking about," House says, giving Kumar a point of victory. Kumar nods humbly while inside he jumps for joy.
Back in the South Pole, Sean is instructed to take off Cate's socks. He does, and lo and behold, there's a big ol' broken toe. This is the first Cate's seen of this, since it's so cold down there and the heat inside apparently sucks so bad that her feet are always numb, so she never felt the pain of a very broken toe. Meanwhile, bits of bone marrow were leaking out of the broken bone and entering her circulatory system, where they caused havoc. Now all they have to do is close the break. It's going to suck, but Sean drank pee and drilled a hole in Cate's skull, so he's ready to do this, too. And it'll hurt Cate a lot more than it'll hurt him. Foreman tells Sean what to do while House looks away. We hear a particularly unpleasant sound and Cate screams bloody murder. But then it's over, and Cate thanks House. House tells her Sean is the person who saved her life, because to take credit for anything would mean Cate might like him and then he wouldn't get to be so miserable. Or maybe he'd be more miserable. Either way, he's going to stay with the status quo. Sean and Cate hug. House turns the screen off. "He likes her," he says.